Many pipelines currently in operation have become structurally deficient due to corrosion, erosion or other causes which damage the structural integrity of the pipeline. Some structural deficiencies may have been caused by defects in the original design, defects in the manufacturing process, incorrect installation, or the effects of corrosion due to age. These structural deficiencies may be intermittent or continuous in nature. In addition, some pipeline systems have increased operating demands and would benefit from an increase in the allowable pressure of the existing pipe and the corresponding flow capacity increase.
The operators of these pipelines are frequently dependent on the pipelines and are unable to discontinue use without severe consequences. Often it is not economically feasible to replace the system, such as when the deficiencies are intermittent in nature or when the pipeline cannot be taken out of service.
Whether the pipelines are transmitting water or some other fluid, the passage of time results in increased incidents of leakage and increasing concerns over the structural integrity of the pipeline. In some situations, a new pipeline can and will be constructed to replace the existing pipeline. The new pipeline will be placed in service and the old pipeline removed or simply abandoned. In many situations, however, the replacement of the pipeline is economically or functionally infeasible. The cost may be prohibitive. Constructing a parallel pipeline may be difficult or impossible and retaining the existing pipeline in service may be essential. Thus, in many situations, a system and method for reinforcing or repairing an existing pipeline while retaining the pipeline in service is seriously needed.
A number of systems and methods have been developed for repairing pipeline segments in place, such as the system and method disclosed in U.S. Pat. No. 7,165,579 to Borland, et al. Each of the prior art systems and methods have provided a technically feasible system or method for making a repair to the existing pipeline, and have done so with varying degrees of success. Many of the pipelines needing reinforcement or repair are large diameter, exceeding 12 feet in diameter, and have inconsistent external dimensions or have external mortar coatings. Prior art systems are not easily adaptable to these pipe sizes or external surface irregularities. Prior art systems utilize and require rigid enclosures to assure that a gasket maintains intimate contact with the existing pipeline and the enclosure so as to provide that the system is sealed. Some prior art systems are connected to the existing pipeline in such a way as to render them inflexible.
Prior art disclosures include systems utilizing half-shell enclosures wherein bolts are utilized to rigidly center the half shells around the existing pipeline and gaskets combined with hardware provide end seals to allow injecting resin at high pressure into the annular void. Such a system is limited to use with existing pipe having very accurate and uniform pipe dimensions and gasket seats for such a system require a rigid cylinder for the enclosure in order for the gasket to seal during pressurization. Further, a gasket seal system does not provide an effective means to seal against a concrete or mortar coated pipeline. In contrast the current invention provides a flexible enclosure with passive centering means, including end seals which allow the enclosure to be rounded upon pressurization. Unlike many other prior art devices, the seal rings and the seal retainers of the current invention do not interfere with joining multiple overlapping enclosures to provide a lengthened sealed enclosure system. Embodiments of the enclosure of the present invention allow maintaining a seal against an irregular surface such as concrete or mortar coated pipelines. When combining the enclosure system of the present invention with the pipeline support system of the present invention, the work space requirements such as the excavation for a buried pipeline will be minimized. This support system also provides the means to continue with multiple enclosures while supporting the existing pipeline or enclosure.
Other prior art disclosures include repair systems which include custom fabricated shapes intended for a specific localized repair and do not provide for adjustments necessary for irregularities in the existing pipeline. Also, they are intended for localized repair and do not provide for interconnecting enclosures to create a continuous and extendable repair. For these systems, rounding of the cylinder is prohibited as the geometry of the fabricated shape causes the cylinder to become rigid. Bolted embodiments of these systems require a rigid structure in order for the bolted assembly to retain its shape and seals. A tapping tool is utilized to pierce the existing pipeline and pressurize the annular space within the enclosure. Such systems seem well suited for repair of petroleum pipelines with uniform external dimensions.
Other prior art systems provide a clamp style repair device and utilize a liquid sealant. These systems require a rigid structure which is further complicated by the need to heat the device before installing to assure a shrink to fit assembly will seal the device edges. These devices are intended for a localized repair and for use with existing pipelines with uniform existing pipe dimensions to work properly. The protruding hardware of these systems makes the use of coatings for corrosion protection very difficult and indicates the system is only intended for localized repairs.
It is an objective of the present invention to provide a system and method for pipeline reinforcement which is more economical, both as to materials and labor, easier and faster to install, and more reliable than the prior art systems and methods.
It is a further objective of the present invention to provide a pipeline reinforcement system and method that provides for the ready reinforcement of contiguous segments of pipeline.
It is a further objective of the present invention to provide a pipeline reinforcement system and method that provides for the ready reinforcement of contiguous segments of pipeline; provides for the temporary suspension of pipeline reinforcement construction, leaving the reinforced sections in a structurally sound condition; and provides for the resumption of pipeline reinforcement construction for sections contiguous to sections completed prior to the suspension at a later date without the need for modification to the system.
It is a further objective of the present invention to provide a system and method for repairing stretches of pipeline involving multiple pipeline segments with a continuous external pipe enclosure.
It is a further objective of the present invention to provide a pipeline reinforcement system and method which provides a round and cylindrical reinforcement pipe, for each section of existing pipe reinforced, regardless of whether the existing pipeline is round or out-of-round.
It is a further objective of the present invention to provide a system and method for pipeline reinforcement that uses a “flexible” pipe design for a pipe enclosure. The meaning of the term “flexible” as applied to reinforcement pipe sections for purposes of this application is provided hereafter.